The invention relates to a yarn texturing machine of the type disclosed in WO 98/33963 and corresponding U.S. Pat. No. 6,209,302.
In the known texturing machine, a plurality of feed yarn packages are arranged in a creel frame, one on top of the other. Each feed yarn package supplies a yarn to a processing station in the machine. For unwinding and for advancing and possibly drawing the yarns, a plurality of feed systems are arranged in the machine, one after another. In this arrangement, the first feed system is arranged above the creel frame to withdraw the yarn from the feed yarn package and to advance it into a false twist texturing zone. This arrangement permits advancing the yarn without deflection from the feed system directly to a heating device within the false twist texturing zone. However, at the beginning of the process, it is necessary that for threading the yarn, the feed system be moved from its operating position to a servicing position. To this end, the feed system is mounted on a slide, which can be moved by means of a linear drive along a guide rail. In so doing, it is necessary to overcome considerable differences of height between the upper operating position and the lower servicing position. This requires a transfer of a large force for the movement of the slide with the feed system. Furthermore, it is necessary that the feed system be very accurately positioned in its operating position, so that the advance of the yarn in the downstream heating device can take a desired course for the treatment of the yarn.
Furthermore, the two feed systems may be driven at a speed difference, with the first feed system being operated at a lower speed in relation to the second feed system. In the known texturing machine, the feed system upstream of the texturing zone is designed and constructed as a feed roll, which advances the yarn by friction, substantially without slip, in a track extending on its circumference. To apply to the yarn the frictional force needed for the advance, it is necessary to have a minimum looping on the circumference of the feed roll as well as a yarn track for a transverse deflection of the yarn in the looping region. However, such a design and construction of the feed system requires in a first threading of the yarn, a minimum yarn tension for inserting the yarn into the track of the feed roll. Furthermore, the speed difference between the adjacent feed systems, as well as the friction exerted by the feed roll on the yarn during its threading lead to substantial differences in the yarn tension. However, the threading of the yarn, during which the speeds of the feed systems are varied, is possible only to a limited extent, when the drives of the feed systems of adjacent processing stations are coupled.
It is therefore an object of the invention to further develop the texturing machine of the initially described kind such that an operator can perform the vertical adjustment of the feed system and the threading of the yarn without significant physical effort. Furthermore, it is the object of the invention to create a texturing machine, wherein upon reaching the operating position of the feed system, the yarn can be gently threaded in a processing station of the texturing machine despite speed differences in the feed systems and without significant changes in the yarn tension, and wherein it can be gently inserted into the heating device.
The above and other objects and advantages of the present invention are achieved by the provision of a yarn texturing machine which comprises a plurality of serially arranged yarn feed systems. At least one of the feed systems comprises a driven feed roll which is partially looped by the advancing yarn so as to advance the yarn by friction in a guide track on the feed roll. A guide member is mounted for movement relative to the feed roll so as to vary the extent of the looping between a threading position and an operating position. In the threading position, the yarn does not contact the feed roll, and in the operating position the yarn is in contact with the feed roll.
The one yarn feed system may also comprise a slide which is displaceable along a guide rail between a servicing position and an operating position. The slide is guided along the guide rail by means of a slide element which slideably engages the guide rail. Also, a drive is coupled to the slide or the slide element via a connecting means, so as to move the slide between the two positions.
The texturing machine of the present invention distinguishes itself in that irrespective of its positions, the feed system can be guided along the guide rail with a uniform stability. The yarn may advance in the feed system already in the servicing position, since the transverse forces that are transmitted by the yarn to the feed system, are safely absorbed by the guided slide, when the feed system is moved.
The connecting means between the drive and the slide element is designed and constructed such that until the operating position is reached, it ensures a reliable guidance of the slide element in the guide rail, and a transfer of force for a uniform movement.
In a particularly advantageous further development of the invention, the connecting means is formed by a magnetic piston, which is guided in a cylinder by means of compressed air, and which connects to the slide element by magnetic forces. The direct connection between the slide element and the piston controlled by the drive makes it possible to position the slide and thus the feed system in a very accurately reproducible manner, which stabilizes the yarn advance in the operating position.
The combination of a cable line and the drive allows large weights and long distances to be handled in an advantageous manner. To this end, the slide element guides the slide with the feed system along the guide rail. The drive is preferably connected to the slide element, via a cable line, which extends along the guide rail. Thus upon actuation of the drive, only one force acts upon the slide element in the direction of movement. The force is transmitted by the cable line, thereby eliminating disturbance variables by transverse forces. Preferably, the drive is formed by a piston-cylinder unit, wherein the piston in the cylinder is controlled by compressed air. With that, it is possible to move the feed system fast and precisely between the lower servicing position and the operating position. However, it is also possible to hold the feed system in an desired position between the servicing and the operating position. Such a holding position can be realized by applying pressure to both sides of the piston within the cylinder.
To enable a sensitive control of the movement of the slide, the cable line may comprise two cables, which are connected to the opposite ends of the slide element, and guided to the cylinder respectively over an upper and a lower pulley. The cylinder extends parallel to the guide rail, so that the cables each extend into the cylinder through an inlet provided at each end of the cylinder, and connect to the opposite ends of the piston.
To avoid major pressure losses while controlling the cylinder, it is proposed to arrange a seal in each inlet of the cylinder, through which the cable extends.
According to one specific embodiment, a control valve is used for controlling the piston-cylinder unit. The control valve is designed and constructed such that the piston is controllable both in its direction and in its speed, so that the movement of the slide element is variable in its direction of displacement and in its speed of displacement. This development is especially of advantage for moving the feed system into its operating position. In this connection, it is possible to reduce the speed of displacement shortly before reaching the operating position, so that a slow and, thus, safe entry into the operating position is possible. This is especially advantageous for inserting the yarn into the heating device. In such texturing machines, it is preferred to use heating devices, in which the heating surfaces have a temperature that is higher than the melt point of the yarn material. Thus, it is possible to avoid by the slow entry into the operating position that the yarn comes into an unacceptable contact with the heating surface and thereby melts or burns.
In a further development of the texturing machine according to the invention, the slide with the feed system connects to the slide element by a pivoting means. In this instance, the slide can be pivoted in the operating position by the pivoting means from a sliding position to a deflected position, and vice versa. This development provides a further solution to the underlying problem. The special advantage of this feature lies in that in the deflected position of the slide, the feed system has reached its final operating position. With that, it is possible, for example, to insert the yarn into the heating device alone by adjusting the slide between the sliding position and the deflected position. The movement of the pivot mechanism may be controlled, for example, by moving against a stop or by a separate drive. Furthermore, it is possible to influence thereby the yarn looping, so that the looping friction on the feed system, which is necessary for advancing the yarn, is reached only in the deflected position.
In this embodiment, a push element is mounted next to the slide element for sliding on the guide rail. The slide element and the push element connect to the slide by the pivot mechanism. The movement of the pivot mechanism is effected by a relative movement between the slide element and the push element on the guide rail. This permits controlling the pivot mechanism in its movement by the linear drive, so that both the vertical adjustment and the swing motion of the feed system can be performed by a simple manipulation.
To realize a possibly compact structural unit, it is proposed to construct the pivot mechanism as a simple push crank. To this end, the slide connects, via a pivot axle, to the push element. Between the slide element and the slide, a rocking arm extends with pivot joints. This permits turning the slide about the pivot axle by a relative movement between the slide element and the push element.
The relative movement between the push element and slide element is easy to realize by simply blocking the nondriven element relative to the driven element. In the present case, the slide element connects to the linear drive, so that for releasing the relative movement, the push element must be blocked on the guide rail.
To this end, a stop is provided at the end of the guide rail, which the push element reaches in the operating position. Once the push element engages the stop, the continued drive of the slide element by the linear drive leads to a deflection of the slide guided on the rocking arm. In this instance, it will be especially advantageous, when the push element precedes the slide element on the guide rail in the direction of movement to the operating position. This permits securing the deflected position by the contact of the slide element with the push element.
Preferably, the pivot mechanism assumes in the deflected position of the slide in relation to the slide element and the push element, such a position that the transmitted forces lead to an automatic over-the-center locking of the slide element and the push element on the guide rail. Thus, the feed system is securely locked in its operating position. The automatic locking will release only when the slide element is activated by the linear drive to move to the servicing position.
In the texturing machine of the present invention, the feed system may be vertically adjusted with or without the drive of the feed system. In the case that the drive is mounted to the slide together with the feed system, and adapted for moving from the operating position to the servicing position, the drive may be designed to connect in the operating position to an energy supply outlet. Depending on the construction of the drive, it is thus possible to provide a connection between a source of energy and the drive by means of a mechanical coupling or an electrical plug contact.
In a particularly advantageous further development of the texturing machine, the feed system is designed and constructed as a feed roll, which comprises on its circumference a zigzag yarn guide track. Such a feed roll is known, for example, from DE 196 52 620. To reach the speed of advance, it is necessary that the yarn loop about the feed roll to a certain degree. Thus, it is possible to influence with advantage the degree of looping about the feed roll by adjusting the slide between the sliding position and the deflected position. The deflected position thus requires a large looping, whereas the sliding position needs only little looping, which must facilitate only a threading of the yarn in the servicing position.
With the use of a feed roll, it is known that a feed roll advances the yarn without slip, only when the frictional forces acting upon the yarn are sufficiently high. In this connection, the frictional forces are produced by the yarn loopings about the feed roll and guide elements of the feed roll. If the frictional forces are too low, a slip will occur between the yarn and the feed roll, i.e., the yarn will slide relative to the contact surfaces of the feed roll. This effect is now being used in particular for threading the yarn, and leads to a further solution to the underlying problem. To this end, when a yarn is threaded by means of a guide member in a processing station of the texturing machine according to the invention, the yarn is initially advanced by at least one adjacent feed system without contacting the guide track on the circumference of the feed roll. In this phase, the yarn advances at a speed, which is determined by the adjacent feed system. For drawing the yarn, the speeds of the feed systems differ, so that a draw tension is able to build up in the yarn. The speed difference or the draw tension is slowly built up by moving the guide member, until the guide member reaches the operating position. This allows a sudden deceleration or an acceleration to the differential speed of the adjacent feed system to be avoided. This solution also has the advantage that it thus facilitates threading in a stationary feed system.
In a particular advantageous further development of the invention, the guide member advances the yarn only in its threading position. In the operating position of the guide means, the yarn is advanced exclusively by the feed roll. The guide member has no contact with the yarn. This development has the advantage that no additional yarn deflection and, thus, no looping friction by the guide means occur, while the yarn is being processed. By the movement of the guide member, the yarn is transferred to the feed roll.
To deflect the yarn as little as possible in the threading position, the guide member takes the form of a threading plate which is arranged in spaced relationship with the feed roll, so as to cover the yarn track and, thus, the guide elements of the feed roll. In the threading position, the yarn is thus guided on the surface of the threading plate.
A particularly compact construction, as well as a particularly gentle yarn guidance can be realized wherein, in relation to the feed roll, the threading plate exhibits a similar curvature, so that in the threading position, the deflection of the yarn can be made uniform and especially small over the entire looping range. The movement of the threading plate in the circumferential direction of the feed roll effects in addition a gentle entry of the yarn into the guide track of the feed roll.
To be able to influence the degree of the yarn looping on the threading plate in the threading position or the degree of the yarn looping about the feed roll in the operating position, it is proposed to mount on the threading plate an inlet yarn guide and an outlet yarn guide, which face each other at a distance in the circumferential direction of the feed roll.
The movement of the guide member can be realized in a simple manner by a rocking arm. This rocking arm is mounted with its one end in a pivot bearing.
A particularly advantageous development of the texturing machine according to the invention provides for a guide arrangement, which comprises a guide groove concentric with the circumference of the feed roll. In this guide groove, the guide means extends between the threading position and the operating position.
In this development, the movement of the guide member may be performed both by an independent drive or by auxiliary yarn threading devices.